| 摘要 |
<P>PROBLEM TO BE SOLVED: To increase a light deriving efficiency and suppress a color shift in a light emitting device wherein, to achieve such a light emitting device as a white light source, its light emitting element of a light emitting diode, etc. is contained in a dome-form wavelength converting member, and the light radiated from the light emitting element is made outgoing by converting it into a desired-wavelength light. <P>SOLUTION: In the light emitting device, the cross-sectional shape of the outer surface of a transparent member 5 to become a light outgoing surface to air is so formed as to be a semi-ellipse R. The focuses F1, F2 of the semi-ellipse R are the two intersections where the outer tangential circle of a light emitting element 2 intersects a surface to perform the luminous-intensity control of the device. Further, the gap angle θ between the normal V at each point P and the line segment of the point P and the focus F1 (F2) is so set as to be smaller than the total-reflection angle of the transparent member 5. That is, the semi-ellipse R is so set as to fall within the scope between a semicircle R2 and a semi-ellipse R1 whose gap angle is smaller than the total-reflection angle of the transparent member 5. Therefore, while preventing the total reflection in the light outgoing surface of the transparent member 5 in comparison with a shell type shape, etc., a wavelength converting member 7 is so made to approximate closely to the light emitting element 2 that the light having a high center luminance and a few color shift can be obtained, that the light radiated from the side surface of the device is reduced, further, that the light deriving efficiency to the front-surface direction of the device can be increased. <P>COPYRIGHT: (C)2008,JPO&INPIT |
